The nested-restore test only checked that an unresolvable inner agent
left its tool call in the checkpoint for a later retry. It did not
verify what happens to a sibling inner agent that does resolve and
complete during the same restore.
Add a resolvable done-agent alongside the missing inner-agent and
assert that its progress is persisted: its inner checkpoint is dropped
and its result recorded as a completed call, so a later retry replays
only the still-unresolved branch instead of re-running finished work.
Signed-off-by: Bryan Frimin <bryan@probo.com>
fc21d65c63